open paths heatmap
Uses NodeJS and heatmap.js to create an HTML5/ canvas heatmap from Open Paths location data.

realtime multiplayer in html5
Read the full article: http://buildnewgames.com/real time multiplayer/ An example using node.js, socket.io and HTML5 Canvas to explain and demonstrate realtime multiplayer games in the browser.

Sketchplain
A social interactive sketching game powered by HTML5 Canvas and Node.js.